[2.0.49] Construction bots may deadlock

Bugs that are actually features.
gyorokpeter
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[2.0.49] Construction bots may deadlock

Post by gyorokpeter »

To reproduce:
- Have a storage chest filled with items for which it is the only chest in the network that will accept it
- Try to move the chest by cutting and pasting it
This results in construction bots picking up the items from the chest and getting stuck in the air as they have nowhere to drop the items. Normally this should last until the chest is built at the new location, but in this scenario, the chest never gets built, despite there being spare chests and idle bots in the network. I guess the task of building the chest is over-optimistically assigned to one of the bots taking items from the chest, and is not reassigned to another bot when the original bot fails to finish its task on time. The workaround is to either manually build the chest or deconstruct the ghost and then immediately undo the deconstruction.
Attachments
bots-stuck.png
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Loewchen
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Re: [2.0.49] Construction bots may deadlock

Post by Loewchen »

Creating a situation where at some point there is no storage capacity available is a user error, and this one is easily recoverable anyway.
gyorokpeter
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Re: [2.0.49] Construction bots may deadlock

Post by gyorokpeter »

Loewchen wrote: Thu May 15, 2025 10:14 am Creating a situation where at some point there is no storage capacity available is a user error, and this one is easily recoverable anyway.
Actually this is a regression introduced by https://factorio.com/blog/post/fff-374. Before the possibility of having one bot do multiple tasks, this deadlock could not occur.
Loewchen
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Re: [2.0.49] Construction bots may deadlock

Post by Loewchen »

Ofc it could, all you need is more items in the chest than your bots can carry.
robot256
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Re: [2.0.49] Construction bots may deadlock

Post by robot256 »

This is another example of why the construction bot scheduler needs a timeout to reassign jobs away from "delayed" robots. It would somve the issues with tile build order and elevated rail support assignment too. I added context to the suggestion:

viewtopic.php?t=128817
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